Fixing member

ABSTRACT

A fixing member comprising a tie bar (4) having an expandable buffer (5) mounted thereon, the buffer being surrounded by a split ring (14) which is shorter than the length of said buffer (5), said expandable buffer bearing against an endpiece (6) linked to one end of the tie bar, and a nut (11) being screwed onto the opposite end of the tie bar to compress the expandable buffer (5) axially, thereby causing both the buffer and the split ring (14) to expand radially, the fixing member being characterized in that the inside surface of the split ring (14) has a helical groove (17).

BACKGROUND OF THE INVENTION

The present invention relates to a fixing member for being received inand fixed securely to a cylindrical hole in a wall of any kind, themember serving to fix, suspend, fasten, etc. an object of some kind.

More particularly, the invention relates to a fixing member comprising atie bar having an expandable buffer mounted thereon, the buffer beingsurrounded by a split ring which is shorter than the length of saidbuffer, said expandable buffer bearing against an endpiece linked to oneend of the tie bar, and a nut being screwed onto the opposite end of thetie bar to compress the expandable buffer axially, thereby causing boththe buffer and the split ring to expand radially.

FIG. 5 of French patent No. 1 056 501 shows an anchor device of thistype in which the tie bar is constituted by a bolt 19 whose head 20serves as an abutment for the buffer 4. The buffer is surrounded by asplit sleeve 5 having a plurality of slots, which slots naturally do notextend over the full length of the sleeve. The assembly is inserted intothe cavity and the buffer 4 is compressed by a tapped rod 16 whichserves as a nut and which is screwed onto the end of the shank of thebolt. The outside of the sleeve 5 is rough.

SUMMARY OF THE INVENTION

The present invention seeks to improve that type of fixing member so asto enable it to provide fixing which withstands a much higher extractionforce.

Thus, the present invention provides a fixing member as defined above,and characterized by the fact that the inside surface of the split ringhas a helical groove.

In has been observed that this technique is very important in obtainingan extraction force which is very high, and is much more important thanhaving roughness on the outside surface of the ring.

According to another characteristic, the ring has a single slotextending over its entire length, thereby enabling the ring to expanduniformly over its entire length.

This slot is preferably made obliquely so that the absence of force isnot localized on a generator line.

BRIEF DESCRIPTION OF THE DRAWING

Other characteristics of the invention appear from the followingdescription of an embodiment of the invention made with reference to theaccompanying drawing, in which:

FIG. 1 is a section through a fixing member of the invention;

FIG. 2 shows a part of the fixing member shown in FIG. 1;

FIG. 3 is an end view of the part shown in FIG. 2; and

FIG. 4 is a view on a larger scale showing a detail IV of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the example described, the fixing member is used to enable a load 3which may be a maintenance machine, for example, to be suspended from atube plate 1 fitted with tubes 2 in a water box of an apparatus such asa condenser, a reheater, a steam generator, etc.

The fixing member is thus intended to be fixed inside a tube 2. Itcomprises a tie bar 4 having an expandable buffer 5 fitted thereover.The buffer 5 is sandwiched between an endpiece 6 which is screwed ontothe end of the tie bar and a sleeve 7 which is threaded over the otherend of the tie bar. A thrust piece 8 is interposed between the sleeve 7and the expandable buffer 5. In addition, in order to prevent the tiebar 4 from rotating, it includes a square 9 over which a square sectionbore 10 of the sleeve 7 is fitted.

A nut 11 is screwed onto the end of the tie bar over which the sleeve isdisposed and it bears against the sleeve via a ball bearing abutment 12.The nut 11 is provided with a slot 13 to enable it to be screwed ontothe tie bar 4 by means of a calibrated torque screwdriver.

Tightening the nut 11 thus moves the endpiece 6 and the sleeve 7 towardseach other, thereby compressing the expandable buffer 5 axially and thuscausing it to expand radially.

A split ring 14 is disposed around the expandable buffer 5. The lengthof the ring 14 is naturally shorter than the length of the expandablebuffer 5 so as to allow the buffer to be compressed axially. The insidesurface of the ring has a helical groove 17. As a result, while thebuffer 5 is being compressed, its outside surface penetrates into saidgroove and ensures perfect adhesion between the buffer and the ring.

FIGS. 2, 3, and 4 show the ring 14 in detail. It can be seen that theslot 15 in the ring is oblique and does not run along a generator line.In addition, it can be seen that the outside surface of the ring alsohas a helical groove 16 whose pitch is 1 mm, for example. During regularexpansion of the expandable buffer 5, and in like manner to the groove17 relative to the buffer 5, the groove 16 serves to obtain goodadhesion between the ring 14 and the tube 2.

By virtue of this ring 14 which is specially provided with the outsidegroove 16, the radial force exerted on the tube 2, or more generally ona cylindrical hole in a wall of any kind, is well distributed in uniformmanner making it possible to obtain fastening that withstands a veryhigh extraction force.

The slope of the slot 15 prevents absence of force from concentratingalong a generator line.

By way of example, tests have shown that in an application where thefixing member is inserted in a tube of a tube plate, a force of about400 kg is required to extract the fixing member. This result is obtainedwith a low pressure on the inside wall of the tube and with lowtightening torque (of the order of 400 gram-meters) on the nut 11.

When the member is to be installed and fixed remotely, e.g. under remotemanipulation or by a robot, the traction force on the tie bar 4 may beobtained by fitting all kinds of positive actuators thereto, e.g. underelectrical, pneumatic, hydraulic, electromagnetic, . . . , control,instead of using the nut 11.

I claim:
 1. A fixing member comprising a tie bar (4) having anexpandable buffer (5) mounted thereon, the buffer being surrounded by asplit ring (14) which is shorter than the length of said buffer (5),said expandable buffer bearing against an endpiece (6) linked to one endof the tie bar, and a nut (11) being screwed onto the opposite end ofthe tie bar to compress the expandable buffer (5) axially, therebycausing both the buffer and the split ring (14) to expand radially, thefixing member being characterized in that the inside surface of thesplit ring (14) has a helical groove (17).
 2. A fixing member accordingto claim 1, characterized in that the split ring (14) has a single slot(15) extending over its entire length.
 3. A fixing member according toclaim 1, characterized in that the slot (15) extends obliquely.
 4. Afixing member according to claim 1, characterized in that a sleeve (7)is threaded over the tie bar (4) between said expandable buffer (5) andsaid nut (11).
 5. A fixing member according to claim 4, characterized inthat the tie bar (4) includes a square (4) engaged in a square sectionbore (10) of said sleeve (7).
 6. A fixing member according to claim 4,characterized in that a ball bearing abutment (12) is interposed betweensaid nut (11) and said sleeve (7).
 7. A fixing member according to claim4, characterized in that a thrust piece (8) is interposed between saidsleeve (7) and said expandable buffer (5).